docs: def is_class(data):
      """
      checks that the data (which is a string, buffer, or a stream
      supporting the read method) has the magic numbers indicating it is
      a Java class file. Returns False if the magic numbers do not
      match, or for any errors.
      """
  
      try:
          with unpack(data) as up:
              magic = up.unpack_struct(_BBBB)
  
          return magic == JAVA_CLASS_MAGIC
  
      except UnpackException:
          return False